Shut-off damper

ABSTRACT

A shut-off damper which can be actuated by an air cylinder and closed so that there is substantially no leakage passed it. A bearing surface on the damper is urged against a seating surface on the duct sufficiently to form a hermetic seal.

a 4 United States Patent 1 [111 3,724,809

Reale 1 Apr. 3-, 1973 [54] SHUT-OFF DAMPER [56] References Cited [75 Inventor: Salvatore J. Reale, Wayne, NJ. UNITED STATES PATENTS [73] Assignee: Foster Wheeler Corporation, Living- 709,102 9/ 1902 Martin ..25l/204 X ston NJ. 955,948 4 1910 Davis 2,013,212 9/1935 Hollander [22 Filed; Nov. 1, 1971 2,841,360 7/1958 Gustavsson ..25l/298 X [21] Appl' 1943 Primary Examiner-Harold W. Weakley Attorney-John Maier, III et al. [52] U.S.Cl..... ..251/58, 251/62,25l/l88,

. 251,298 [57] ABSTRACT [51] Int. Cl. ..F16k 31/16 A shutoff damper'which can be actuated by an' air [58] Field ol'Search ..251/58, 62, 187, 108, 204, cylinder and closed so that there is substantially n leakage passed it. A bearing surface on the damper is urged against a seating surface on the duct sufficiently to form a hermetic seal.

4 Claims, 3 Drawing Figures PATENTEnAPRs ma sum 1 OF 2 SALVATORE J REAL? I N VENTOR BY%,(,

PATENTED R I975 8.724.809

SHEET 2 [IF 2 SALVATORE J REALE INVEINTOR BY ATTflR/VEY SHUT-OFF DAMPER BACKGROUND OF THE INVENTION In power plants using coal-fired furnaces, several mills are usually provided to pulverize the coal so that it can be fed to the burners by a stream of compressed air. The mills are usually connected by common duct work so that they all feed pulverized coal through the ducts to the furnace. This arrangement permits a mill to be shut-down for service, inspection or repair while the remaining mills provide fuel for the furnace. Such operations usually necessitate service personnel going into the mill, an unpleasant task because the mill is fed with hot air which during normal operation forces the pulverized coal through the mill and to the burners and during shut-down, this air tends to leak into the mill. Consequently, working conditions in a shut-down mill are unpleasant and often unacceptable because of the heat and the coal dust which circulates in the mill because of the hot air moving in the mill.

In the past, a solution to this problem has been attempted by the use of dampers which are essentially steel doors pivoted on one side of the duct through which the mill is fed hot air. The damper can be closed simply by pivoting it.

This arrangement has several drawbacks. For one, because the steel door is welded and otherwise stressed during fabrication, some warpage is inevitable so that bearing surfaces on the door will not make perfect contact with seating surfaces on the duct work.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome drawbacks found in the prior art such as those discussed above. Accordingly, a damper pivoted on one side to a side wall of a duct through which hot air is fed to a pulverizing mill is provided with wedged blocks engaged by spiral arms which can be turned from outside of the duct to exert considerable force against the blocks to thereby cause the bearing surface of the damper to engage against a seating surface to prevent leakage past the damper.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view partly in section of a'duct provided with a shut-off damper of the present invention;

FIG. 2 is a side view partly in section showing a portion of the structure shown in FIG. 1 but in an enlarged scale; and

FIG. 3 is a view partly in section taken substantially along the line 3-3 of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 a straight section of duct work which conducts hot air to a coaI-pulverizer is provided with a shut-off damper 12 which is pivoted at one end at 14 to a side 16 of the duct 10 so that the damper 12 can be moved from an open position such as shown in dotted line of FIG. 1 to a closed position such as shown in closed line in FIG. 1. In the closed position, marginal edge portion 18 of the damper 12 engages, at a bearing surface in form of gasket 19, on the seating surface 20 of the duct 10. The gasket 19 extends over the entire length of the bearing surface 18 which is adjacent to the periphery of the damper 12. In other words, the gasket 19 conforms more or less to the seating surface 20 which extends around the duct 10.

In order to move the damper 12 from its open position to its closed position, an air cylinder 22 is provided. The air cylinder 22 is mounted on a mounting plate 24 on the ends of outwardly projecting wall section 26 which is intregal to the duct 10. The air cylinder 22 has a piston rod 28 which at its end has a pin 30. The

pin 30 rides in a slot 32 in a follower plate 34 which is secured to the shut-off damper 12 adjacent to the portion 18 thereof. As shown in the drawings, the follower plate 34 is generally perpendicular to the shut-off damper 12.

When it is desired to close the damper 12, the air cylinder 22 is actuated so that the piston rod 28 moves axially to the left as shown in FIG. 1. The pin 30 will move first downward and then upward in the slot 32 as the shut-off damper 12 rotates downward to the shut position to prevent any binding from occurring. To open the shut-off damper 12, it is merely necessary to actuate the air cylinder 22 so that the piston rod 28 moves axially to the right as shown in FIG. 1 until the shut-off damper 12 is in the dotted line position.

It has already been explained how ducts such as 10 must be sealed off effectively from the influx of hot air if the coal-pulverizers they serve are to be serviced by personnel inside of the pulverizer. The seal is especially difficult because of the warpage which occurs in shutoff dampers due to the welding and other work which is done on them during their fabrication. In order to assure that the marginal edge portion 18 seals along its entire length on seat 20, considerable bearing forces are applied on the marginal portion from outside of the duct 10.

To this end, a series of blocks 42 (FIG. 3) each with a beveled surface 44 are spaced along the marginal edge portion 18 on the side of the damper 12 other than that on which gasket 19 is mounted. A number of threaded rods 46 project through the side wall of the duct 10 and move axially when turned because of their threaded engagement with the side wall or other appropriately threaded members such as nuts 48. At the end of each of the threaded rods 46 and more or less perpendicular to it is a spiral arm 52. The spiral arm 52 extends over the beveled surface 44 of the block 42 and is curved so that it is always over the block 42 as the rod 46 is turned. The outer end of the threaded rods 46 are provided 'with bar handles 54 so that they can each be rotated to turn the associatedrods 46 and thus axially move the rods 46. The rods are threaded so that as each is rotated, the associated arm 52 will move toward the adjacent beveled surface 44. Since it will engage the beveled surface 44 under it as it rotates and moves toward the damper 12, there will be a wedging action at the portion of the bearing surface adjacent to the handle 54 being turned to thereby exert a large force against the marginal. edge portion 18 of the shut-off damper 12. If all of the handles 54 are turned tight, the marginal edge portion 18 will engage tightly against the seat 38 along its entire length.

The foregoing describes but one preferred embodiment of the present invention, other embodiments being possible within the scope of the present invention as defined in the following claims.

What is claimed is:

1. Apparatus for shutting off a duct for feeding hot air to a coal pulverizer comprising:

a duct;

a damper mounted to be rotatable within said duct, said damper having a bearing portion adjacent the periphery thereof;

a seating surface connected with said duct corresponding in shape to said bearing portion, and through which hot air passes when said damper is open but against which said bearing portion engages when said damper is closed;

a number of beveled surfaces each being mounted on said damper adjacent said bearing portion but on the side of said damper opposite to said bearing portion, each of said beveled surfaces being inclined with respect to said damper;

a number of arms; and

means to move said arms relative to said beveled surfaces while each of said arms are in contact with one of said beveled surfaces to urge said bearing surface of said damper against said seating surface 2. The apparatus defined in claim 1 further comprising a power cylinder, said power cylinder being connected with said damper and adapted to open and close said damper.

3. The apparatus defined in claim 1 wherein said arms are each spiral in configuration and connected to I 

1. Apparatus for shutting off a duct for feeding hot air to a coal pulverizer comprising: a duct; a damper mounted to be rotatable within said duct, said damper having a bearing portion adjacent the periphery thereof; a seating surface connected with said duct corresponding in shape to said bearing portion, and through which hot air passes when said damper is open but against which said bearing portion engages when said damper is closed; a number of beveled surfaces each being mounted on said damper adjacent said bearing portion but on the side of said damper opposite to said bearing portion, each of said beveled surfaces being inclined with respect to said damper; a number of arms; and means to move said arms relative to said beveled surfaces while each of said arms are in contact with One of said beveled surfaces to urge said bearing surface of said damper against said seating surface.
 2. The apparatus defined in claim 1 further comprising a power cylinder, said power cylinder being connected with said damper and adapted to open and close said damper.
 3. The apparatus defined in claim 1 wherein said arms are each spiral in configuration and connected to a rod which can be turned from outside of said duct to move each of said arms over a beveled surface, said arms being of a curvature that they are continuously in alignment with said beveled surfaces as said rods are turned.
 4. The apparatus defined in claim 3 wherein each of said rods is threaded so that it moves axially when turned to thereby urge said arms against said block. 